Bottom Bracket

[S-Express]

I am trying to build my old steel Dave Marsh 753 racing frame up to be a good training bike. The frame is pretty small but I think it will fit with long carbon seatpost and handlebar stem

No, I meant what are you trying to do in terms of the topic of this thread - ie the cranks/BB

 

[fossyant]

You have a choice. If you want to use a square taper chainset, then Shimano still do square taper sealed bearing 68mm bottom brackets - Shimano UN54/56

If you want to use a newer chainset, then you need an external BB like Shimano Hollowtech, but you may need the bottom bracket shell 'facing' by a decent LBS first (this ensures the BB external dimensions are 'straight' - external BB's are reliant upon this.

 

[midlife]

I'd be tempted to blow fifteen quid on a 113mm Shimano UN 55 and try that with the 600 chainset.....

Shaun

 

[Ajax Bay]

The 600 cranks would be fine and will need the UN55 I linked to (check chainline/axle length). Do you want to look 'old school'? Do you not want to look old school? Do you care? With STIs on the bars, the bike will not look 'old school'. Not completely clear but I assume you are going for a bar end lever on the left. Could go 'Lance' with FD governed by friction or indexed lever mounted on the downtube. Much shorter and less friction in the cable run.